A basic process for the production of crystalline, semi-crystalline, and amorphous poly(arylene sulfide) polymers from polyhalo-substituted aromatic compounds, wherein the halogen atoms attached to ring carbon atoms react with an alkali metal sulfide in the presence of a polar organic compound at an elevated temperature, is generally known in the art. Due to a continually growing attractiveness towards thermoplastic polymeric resins, a great amount of work has been completed which resulted in the disclosure of methods for both batch and continuous operations to produce crystalline, semi-crystalline, and amorphous poly(arylene sulfide)s from polyhaloaromatic compounds having at least two halogen substituents per molecule. Certain processes for producing crystalline, semi-crystalline and amorphous poly(arylene sulfide) resins result in a liquid reaction mixture comprising a liquid-phase polymer and a polar organic compound which can also function as a solvent for the polymer. Certain other processes for producing poly(arylene sulfide) resins result in a slurry reaction mixture comprising a solid-phase polymeric resin dispersed in a polar organic compound. In order for the polymers produced in these processes to be useful in commercial applications, the polymers must first be recovered from the reaction mixture.
One process used for the recovery of crystalline, semi-crystalline, and amorphous poly(arylene sulfide) resins from a reaction mixture is the addition of a liquid functioning as a phase separation agent. This liquid should be soluble in the reaction mixture and a nonsolvent for the polymeric resin. When certain amounts of a separation agent are used to recover the polymer from the liquid mixture, the process results in the recovery of a polymer in the form of a powder. When certain other amounts of a phase separation agent in the form of a liquid are used to recover the polymer from the reaction mixture, the process results in the recovery of a polymer in the form of relatively large, coarse particles. It should be noted, however, that occasionally some of these resin particles agglomerate into large chunks and/or adhere onto the internal walls of the polymerization reactor. Therefore, it is another object of this invention to provide a method for recovering particulate crystalline, semi-crystalline, and amorphous poly(arylene sulfide) resins from a reaction mixture or liquid mixture comprising a liquid-phase poly(arylene sulfide) and a polar organic compound which can also function as a solvent for the polymer, and optionally water, wherein the resulting polymeric particles are uniform in size and do not tend to adhere to each other or to the internal parts of the reaction vessel.
It is yet another object of this invention to provide a method for recovering particulate crystalline, semi-crystalline, and amorphous poly(arylene sulfide) resins from a reaction slurry comprising a solid-phase poly(arylene sulfide) resin dispersed in a polar organic compound or a slurry prepared by slurrying an already formed resin in a polar organic compound, wherein the resulting polymeric particles are uniform in size and do not tend to adhere to each other or to the internal parts of the reaction vessel.
The invention method can be used to increase the bulk density of an already prepared resin or to achieve a higher bulk density through recovery than would normally be achieved by conventional recovery means. While a technique which increases the resin's bulk density could be advantageous to the commercial industry by improving the resin's handling, there are, however, some applications where such a technique would not be the most preferred mode for improving handling procedures. Specifically, in some commercial applications, it is necessary to have the resin in the form of a fine powder. Examples to such commercial applications include, but are not limited to, powder coating, slurry coating and some types of compounding and pultrusion operations.
If a technique were employed which improved handling procedures by increasing the bulk density of the resin, and if these resins were to be employed in a process requiring the polymer to be in the form of a powder, the resulting resin might have to be milled or ground. Therefore, in those applications wherein it is desirable to use resins while in a powder form, it would be advantageous to improve the handling of the respective resins while not increasing their bulk densities.
It is therefore another object of this invention to provide a method of producing particulate crystalline, semi-crystalline and amorphous poly(arylene sulfide) resins in the form of a fine powder. Surprisingly, the powder produced according to the invention method generally has better handling characteristics, for example, is faster filtering than the powdery resins prepared according to conventional methods.